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dc.contributor.advisorSmith, Andrew David
dc.contributor.authorWu, Jiufeng
dc.coverage.spatialxi, 130 p.en_US
dc.date.accessioned2020-06-30T13:40:10Z
dc.date.available2020-06-30T13:40:10Z
dc.date.issued2020-07-29
dc.identifier.urihttp://hdl.handle.net/10023/20181
dc.description.abstractThe research described in this thesis focuses on probing the reactivity of α,β-unsaturated acyl ammonium intermediates and the use of theses reactive intermediates in a new concept: aryloxide-facilitated catalyst turnover in α,β-unsaturated acyl ammonium catalysis. Chapter 2: Initially, the concept of aryloxide-facilitated catalyst turnover was used in a novel isothiourea-catalysed transfer hydrogenation reaction of α,β-unsaturated p-nitrophenyl esters. An efficient synthetic procedure was successfully developed, which was demonstrated to be applicable to a range of α,β-unsaturated PNP esters (15 examples, 38−98% yield), typically with electron withdrawing β-substituents proving most reactive. Attempts to perform the reaction enantioselectively showed that in principle α,β-unsaturated acyl ammonium intermediates generated from α,β-unsaturated PNP esters and a chiral isothiourea catalyst can react enantioselectively. Chapter 3: Following on the established new concept in α,β-unsaturated acyl ammonium catalysis, enantioselective Michael addition of nucleophiles to α,β-unsaturated PNP esters has been further explored using the aryloxide-facilitated catalyst turnover strategy. This new method was applicable for a range of malonates and malonate derivatives as pro-nucleophiles, resulting in generally good yields with excellent enantioselectivities (14 examples, up to 86% yield, > 99:1 er). This work demonstrated for the first time that simple nucleophiles could be applied in stoichiometric quantities in enantioselective a,b-unsaturated acyl ammonium catalysis. Chapter 4: A detailed variable time normalisation kinetic analysis (VTNKA) was performed to investigate the kinetics of the enantioselective Michael addition of malonates to α,β-unsaturated PNP esters, using 19F{1H} NMR spectroscopic analysis. The order with respect to α,β-unsaturated ester, malonate and catalyst were found to be first order, but zero order with respect to base, indicating the turnover-limiting step is likely to be the Michael addition of malonate to the α,β-unsaturated acyl ammonium intermediate.en_US
dc.language.isoenen_US
dc.publisherUniversity of St Andrews
dc.rightsCreative Commons Attribution-NonCommercial-NoDerivatives 4.0 International*
dc.rights.urihttp://creativecommons.org/licenses/by-nc-nd/4.0/*
dc.subjectOrganocatalysisen_US
dc.subjectAcyl ammonium intermediatesen_US
dc.subject.lccQD505.W8
dc.subject.lcshCatalysisen
dc.subject.lcshAmmonium compoundsen
dc.subject.lcshOrganic compounds--Synthesisen
dc.titleProbing the reactivity of α,β-unsaturated acyl ammonium intermediates in organocatalysisen_US
dc.typeThesisen_US
dc.type.qualificationlevelDoctoralen_US
dc.type.qualificationnamePhD Doctor of Philosophyen_US
dc.publisher.institutionThe University of St Andrewsen_US
dc.identifier.doihttps://doi.org/10.17630/10023-20181


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